Vitamin B.sub.12 is unique among the vitamins in that it contains not only an organic molecule, but also the essential trace element cobalt. Vitamin B.sub.12 is not made by either plants or animals and can be synthesized by only a few species of microorganisms. Bacteria in the human intestinal tract can make enough Vitamin B.sub.12 for normal daily requirements from inorganic cobalt salts in the diet. Vitamin B.sub.12 is also made in large amounts by rich populations of bacteria in the rumen of ruminant animals and in the cecum of other herbivorous species.
Vitamin B.sub.12 participates in many biochemical processes that are essential for life. It acts as a co-enzyme for several enzymes which catalyze the shift of a hydrogen atom from one carbon atom to an adjacent one in exchange for an alkyl, carboxyl, hydroxyl or amino groups. Deficiency of Vitamin B.sub.12 results in the development of the serious disease pernicious anemia. Pernicious anemia, as the name implies, involves a low concentration of hemoglobin resulting from the condition, but the effects also include serious disturbances of the central nervous system that may result in abnormal sensations, motion, and in humans, thought.
Pernicious anemia is usually not due to a dietary deficiency of Vitamin B.sub.12 but rather a failure to absorb the vitamin from the intestine because of deficient secretion of the "intrinsic factor" in the stomach. Put another way, it is a genetic defect of the stomach rather than a dietary deficiency disease. The absorption of the dietary cobalamins depends upon the formation by the gastric mucosa of a carbohydrate rich protein, known as the "intrinsic factor". It is a glycol protein which is required for Vitamin B.sub.12 absorption. Animals with pernicious anemia do not make this protein, and thus are deficient in the intrinsic factor.
In most animals, the cobalt content of the diet is sufficient for the production of the daily requirement of Vitamin B.sub.12. However, ruminant animals, such as cattle, represent a special case because they have a great need for dietary cobalt. Dietary cobalt is essential for the growth and functioning of the rumen microorganisms. The optimal dietary requirements of cobalt for growth and production of Vitamin B.sub.12 by these microorganisms is not known for certain, but an amount of from about 0.5 to about 1.0 milligrams per kilogram of dry matter has been suggested from various studies. Therefore, the diet must contain sufficient cobalt to insure the optimal growth of rumen bacteria. Indeed, supplemetation of poor straw diets with cobalt alone, or cobalt and copper, resulted in significant increases in the overall digestability of crude fiber as well as cellulose degradation. Furthermore, in the rumen, the different bacterial species cooperate to degrade major plant components, particularly cellulose, to D-glucose which is further degraded to lactate, acetate, propionate, and butyrate. In contrast to other mammalian species, in cattle only a few grams of glucose passes from the intestine into the blood stream in a 24 hour period. Nevertheless, cattle need glucose not only to supply energy to the brain and other organs, but also as a source of milk sugar (lactose) in lactating cows. Glucose is formed in the liver from lactate and propionate by gluconeogenesis. The conversion of propionate to glucose requires an enzyme containing Vitamin B.sub.12. Hence, the requirement for Vitamin B.sub.12 is high in cattle, especially lactating cows.
Only a fraction of the ingested cobalt is utilized by the gut microorganisms for the production of Vitamin B.sub.12. It appears that cobalt is transported into bacterial cells by the same transport system as magnesium, and that its uptake depends upon metabolic energy. Thus, it can be seen that it is imperative that the diet, and especially the diet of ruminants, contain an adequate source of cobalt. It is also imperative that cobalt be in a bioavailable form such that it is available for growth and production of Vitamin B.sub.12 by the gut microorganisms.
It is therefore a primary objective of the present invention to provide a highly effective bioavailable form of cobalt in convenient water soluble salt form which is available for use as a feed additive in animal nutrition, especially ruminant animals.
Another important objective of the present invention is the preparation of novel salts of cobalt in which the cobalt is in a form that can readily be absorbed after ingestion by gut microorganisms and utilized in the production of Vitamin B.sub.12.
Yet another objective of the present invention is the preparation of forms of cobalt which are stable, readily soluble in water, and easily and economically manufactured.
An even further objective of the present invention is to provide a method of nutritional supplementation for animals, especially ruminant animals, to assure adequate dietary requirement for growth and production of Vitamin B.sub.12 by microorganisms present in the gut of ruminant animals.
A yet further objective is to provide an easy, simple and direct synthesis route for bioavailable forms of cobalt useful as feed additives in animal nutrition.
A still further objective of the present invention is to provide certain complexed salts of cobalt and certain alpha hydroxy organic acids, such as glyceric acid having coordination bonds formed between the cobalt cation and the alpha hydroxy group of the acid, in addition to the electrostatic attraction between the cation and the carboxyl ions.
The method of accomplishing these as well as other objectives of the invention will become apparent from the detailed description which follows hereinafter.